Porosity tester



Nov. 17, 1953 H. M. BROWN POROSITY TESTER Filed Feb. s, 195o SSS A,

F/G. l'.

INVENToR HUGH-M. Mouw BY ATTORNEY Patented Nov. 17, 1953 UNITED STATS OFFICE 2,659,433 PoitosiTY TESTER Hugh M. Brown,

Clemson, S.

C., assigner to Clemson Agricultural College of South Carolina, Clemson, Carolina acorporation of South This invention relates to a porosity tester such as may be used in testing the relative porosities of various materials.

In such porosity testing, it has heretofore been proposed to pump a fluid through a sample oi the material to be tested, using a single stroke of an expansible chamber iluid pump and timing with means operatively connecting said latch mechanism to the timer to place the latter in operation simultaneously with the release of the latch mechanism and inception of the pump stroke.

Further objects, in accordance with the preferred embodiment of the invention are: to provide means for automatically utilizing a usual mechanical stop watch for the timing function; to provide a novel coordinating means between the stop Watch and a latch mechanism, whereby object in accordance with a modication of the invention resides in the provision of a novel electrically actuated stroke timing mechanism for the pump, including a single timer switch actuated at the beginning and end of the pump stroke respectively to close and open an electrical circuit through the timer.

A still further object consists in the provision of a sample chamber embodying means for compressing` samples of nbrous or other compressihle material therein to a standard volume and thickness.

In this application I show and describe only the preferred modification or my invention, and one modication thereof, simply by Way of illustration ofthe practice of my invention. However,

I recognize that my invention is capable of other and different embodiments and that the several details thereof may be modiiied in various ways, all without departing from my invention. Accordingly, the drawings and description herein are to be considered as merely illustrative and not as exclusive.

In the accompanying drawings:

Figure l represents a vertical sectional View through apparatus embodying the preferred form oi the invention; and,

Figure 2, a diagrammatic View illustrating a modified form of automatic timing means which may be employed with apparatus such as more fully illustrated in Figure l.

'Referring now in detail to the accompanying drawings, and first considering the apparatus illustrated in Figure l, it will be seen that said apparatus embodies a hollow base i adapted to rest on a horizontal surface andliaving a cover Disposed on the base is a sample receiving chamber which is dened in part by a cylindrical resting on the plate il and having its lower end secured in air-tight manner thereto, whereby the bottom wall of said chamber will be dened at il by the plate 2.

VThe upper end of the cylinder or sleeve 3 is closed by a removable weighted lid il having a provided with means which may assume the form oi' a radially projecting ange l to support the lower end the plunger portion t at a predetermined height above the chamber bottom Il. Thus, there is defined a chamber of xed volume, in which a given weight or amount of porous or iihrous material M', when placed in said chamber,

by the be of uniform ber bottom ll.

In order that air or other iiuid might be caused to pass completely through such thickness of material M for the purpose of measuring its porosity, the chamber bottom si is provided with a plurality of uniformly distributed air or liuid inlet ports 8, and the lid E similarly is provided with a plurality of evenly distributed discharge ports or perforations 9 opening through its lower end face and communicating with a central disn charge passage ID which opens into the atmosphere.

Air or other duid may be supplied to the sample chamber by means oi an air inlet manifold II secured in air-tight manner against the lower face of the chamber bottom it in communication with the several ports or periorations il, the manifold in turn being placed in communication with a source of fluid supply through a conduit or tube I2.

Air or other `fluid is supplied through the tube I2 from an expansible chamber fluid pump of the type wherein one end wall of the expansible chamber descends by gravity to expel iiuid Linder constant pressure from the chamber. Such a pump in the preferred embcd'xnent comprises a cylinder I3 fixedly mounted on the upper sui-race of the plate 2 with its axis disposed vertically, and a gravity actuated piston I4 loosely fitted into the cylinder I3 for axial movement. In order that the connections between this pump and the intake mani fold II or the sample chamber may be disposed in an out-of-the-way position beneath plate 2, I provide a small fluid reservoir I5 secured to plate 2 beneath cylinder I3 and in communication with said cylinder through an opening I6 in the plate 2, this reservoir I5 being in communication with the air supply conduit I2, as shown.

In order to vfacilitate the iiow of air into cylinder I3 during the upstrole oi' the piston It, as the piston is reset, I provide an inlet port or ports I'I which in the present instance are disposed in the bottom of the manifold II, these being controlled by a disc checlr valve I8 which is upwardly displaceable on a vertical guide stern Il to permit an influx or air, but which seats against the manifold bottom to close the ports Il against the escape of air from the manifold on the down stroke of the piston.

Extending across the upper end oi the air supply cylinder I3 is a centrally apertured lid or cross-head 2li which may be provided with a port 2I therethrough to place the interior or the cylinder, above the piston Ill, in communication with the atmosphere. A piston rod 22 carried by the piston I4 is freely movable through the central. aperture of the lid 2d and is provided at its upper end with a radially projecting handle '23 by which the piston may be manually raised from the bottom of the cylinder and reset in the position illustrated in Figure l, following its down ward stroke.

As mentioned earlier, the i'luid pump includes a timer and means for automatically initiating the actuation ci the timer simultaneously with the start of the downward movement oi the piston I4, and 'for automatically shutting oli the timer or timing mechanism at the end or the downward movement or strole.

ln the embodiment illustrated in Figure i, the timing means includes a latch Elli which is slidable radially across the top of cylinder I3 (and guided between a pair ci brackets 3B) to and from latching engagement in a notch Z5 in the piston rod 22. rlhe timer in this instance consists oi a usual mechanical stop watch 2t which is supported by a bracket adjacent the upper end of the cylinder il at a location diametrically opposed to the latch 2A. The watch 2li has the usual upwardly spring projected controlling stem 28 which is actuated by downward pressure in known manner both to initiate and to terminate fl its timing function. In other words alternate downward pressures on this stern li will respectively initiate and terminate the operation oi the watch.

The actuation of the watch il?, is coordinated with that ci the latch by oi a bell lever il!) which is pivotally mounted between brackets Sli on the cylinder lid for swinging ,ovement about the axis of the pivotal connection 3l. The longer arm or wn ".iarnetrically across the upA er end o cylinder i3 and has its free end normali' "es-ting on the control stem .'Zil oi stop watch i, v nerehy dovraM ward movement oi Iree end will depress the control stern. 'Normally the resilient upward spring pressure of the stein its will maintain the lever arm 32 in the raised position shown.

It will be noted that rod passes through aperture 33 in the longer lever arm and aperture is enlarged. to permit a l swinging movement or the lever and vertical move ment or the piston rod rThe short depending `arm L oi the lever is suitably connected to the latch ."Zl, as by be ing received in a recess 'iornfd in t e rear end oi latch so that down ard swinging movement oi the longer lever a i f depression or" the watch fl and i. oi the stop watch timing operation, will c. neously cause both the short lever arm latch til to be retracted away the piston rod thus allowing piston lil to descend by gravity in cy- ,der

lt will be noted that the longer arf lever is disposed in the path oi descent o` radially projecting lniob it on the pist so that at the termination or the downw ton stroke this knob or handle will engage arm and push it downwardly again depressing stop watch stem and tern Ahating the operation of the stop watch. Thus it t ll be seen that the actuation ci the stop watch. will be accurately coordinated with the movement oi" the piston ill to automatically time the duration or the downward piston stroke.

Following completion oi a downward strolre, the piston Ml be raised by grasping and littu ing the handle whereupon the la ch will be reset to maintain it in position preparatory to another timed downward stroke.

Prior to actual use oi the invention in test' the relative porosity of various materials, the pi. ton Ill is i'irst allowed to descend while the sample chamber is sealed in any lnown r Cinner against the passage of therethrough. will necessitate that all air expelled from the cylinder It escape upwardly past the loose :dt ton ill. The time required 'Lor filownward piston stroke, as ascertained by sto-p wat 'it in the manner aforementioned, pro'. which when considered in eoniunc i y .th t tota-l volume ci air displaced. by the pis its stroke, will. per'nit ready ascer rate of leakage oi' air the p" son. loose ht or" the piston lc in its will be little wear on the piston and e and `accordingly this particular rate age, once having been ascert red, wil constant over long periods o need only he reA is disposed therein, provides a measure of the In Figure 2 of the drawings I have shown a modified form oi" timing mechanism which may be employed with the air pump of Figure 1 in place or the timing mechanism shown in said iigure. According to thisl modication, the timer is or the electrically actuated clock type adapted to receive electric current through supply wires il@ :and 31.

interposed in one of the supply wires is a normally closed micro-switch 3B which is disposed cooperation with the piston i4 to energize the 'timer circuit simultaneously with the start of the downward piston stroke and to interrupt the timer circuit at the termination of such stroke.

'Ehe switch t has a control member in the form of a lever Sii pivoted to the switch housing at for vertical swinging movement. It will seen that the lever 39 is operable to raise a vertically reciprocable plunger di in the switch housing. This plunger 4l carries a movable switch blade i2 which normally is in contact with stationary switch blade 43 when the switch iree or unoperated. However upward move- The switch is supported in any suitable manner for resilient vertical bodily deflection, as by a spring arm 44 having one end thereof secured to a fixed support d5, the control lever 39 of the switch projecting above and into the path of upward movement of a collar or projection 46 carried by the piston rod, to be raised thereby and maintain the switch open in the raised position of the piston as illustrated in Figure 2. A stop All is fixedly positioned below the control lever 39 to limit its downward movement and to open the switch responsive to bodily downward movement or deection thereof. In order to open the switch coincidentally with the termination of the downward piston stroke, I provide means for deiiecting the switch downwardly, as exemplified by lthe free end or" the spring arm 44 projecting below and into the path of downward movement of the piston rod handle or radial projection 23.

The latch 24E of this embodiment is swingable pivot 24a to and from operative engagement with the piston rod 22, and is pro- 24h swingable into a recess or notch 25 in the piston rod to maintain the piston in raised position, all as shown in Figure 2. If desired, the latch 2e may be resiliently urged toward the piston rod by means such as a coil spring S placed under tension between the free end portion of said latch and a stationary part O.

Thus, as the latch 24 is manually retracted from the piston rod, this will release the piston lil for its downward stroke. The initiation of the downward stroke, with consequent downward movement of the collar 46, will permit the switch lever Se to swing downwardly and close the enerdownward deection of the spring arm 44 and the switch 33 carried thereby will cause the control lever 39 to engage the stop fl'i, and further downward movement of the switch will open the contacts and thereby interrupt the timer circuit.

In order to reset the piston for another automatically timed stroke, it is necessary simply to grasp the handle 23 of the piston rod and raise the piston until the latch 24 resiliently seats in its recess 2li to maintain the piston in raised posiion.

to hold the switch open.

Except for the obvious slight differences incidental to the diferent types of timing mechaby using plungers of different lengths or or diirerent materials such as lead, iron or aluminum.

switch being disposed above movement of the lowerinost of said projections maintain the switch ber for engagement thereby responsive to bodily downward movement of the switch, into the y movement or the uppermost of said projections to be engaged thereby and open the switch at the termination of downward piston stroke.

a piston cylinder, the combinacarried by u spaced lateral projections carried by said rod, a manually operable latch for maintaining the piston in a predetermined raised position, a normally closed timer switch and means supporting same for resilient 7 vertical deection adjacent said rod, a control member vertically movable on said switch and projecting into the path of movement of the lowermost of said projections to open the switch as said member is moved upwardly by engagement with said projection, a stop being xedly positioned below Said control member for engagement thereby responsive to downward deflection of the switch, and means movable with the switch projecting into the path of downward movement of the uppermost oi said projections to be engaged thereby and to open the switch at the termination of the downward piston stroke.

HUGH M. BROWN.

, 1 References Cited in the file of this patent UNITED STATES PATENTS Number 

